Partner of η2（1645） in the 11D2 Meson Nonet

In the qq quark model, the states π2（1670） and η2（1645） are assigned as the I1D2 meson nonet. The partner of state η2（1645） needs further confirmation in the experiments. We employ the meson-meson mixing and the Regge trajectory methods to calculate the mass of the partner of state η2 （1645） to be 1879.8 MeV and 1863 ± 24 MeV respectively. We also calculate the strong decay width in the 3po decay model. These predictions can be compared with experiments in the future.     

Study of X(5568) in a unitary coupled-channel approximation of BK and B_sπ

The potential of the B meson and the pseudoscalar meson is constructed up to the next-to-leading order Lagrangian, and then the BK and B_sπ interaction is studied in the unitary coupled-channel approximation. A resonant state with a mass about 5568 MeV and J~P= 0~+is generated dynamically, which can be associated with the X(5568) state announced by the D0 Collaboration recently. The mass and the decay width of this resonant state depend on the regularization scale in the dimensional regularization scheme, or the maximum momentum in the momentum cutoff regularization scheme. The scattering amplitude of the vector B meson and the pseudoscalar meson is calculated, and an axial-vector state with a mass near 5620 MeV and J~P= 1~+is produced. Their partners in the charm sector are also discussed.     

Radiative decay of the Ξ(1620) in a hadronic molecule picture

Last year,the Ξ(1620) state,which is cataloged in the Particle Data Group(PDG) with only one star,was reported again in the Ξ~-π~+final state by the Belle Collaboration.Its properties,such as the spectroscopy and decay width,cannot be simply explained in the context of conventional constituent quark models.This inspires an active discussion on the structure of this resonance.In this paper,we study the radiative decays of the newly observed Ξ(1620) assuming that it is a meson-baryon molecular state of AK and with spin-parity J~P=1/2~-developed in our previous study.The partial decay widths of the AK-ΣK molecular state into Ξγ and Ξπγ final states through hadronic loops are evaluated using effective Lagrangians.The partial widths for Ξ(1620)~0→γΞ is evaluated to be approximately 118.76-174.21 keV,which may be accessible for the LHCb experiment.If Ξ(1620) is aΛK-∑K molecule,the radiative transition strength Ξ(1620)~0→γKA is considerably small and the decay width is of the order of 0.01 eV.Future experimental measurements of these processes can be useful to test the molecule interpretations of the Ξ(1620).     

Strong decays of P-wave mixing heavy-light 1~+ states

Many P-wave mixing heavy-light 1~+ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1~+ states D0, D~±, D~±s, B0, B~±and Bs are studied by the improved BetheSalpeter(B-S) method with two conditions of mixing angle θ: one is θ = 35.3?; the other is considering a correction to the mixing angle θ =35.3?~+θ_1. Valuable predictions for the strong decay widths are obtained: Γ(D′01)=232 MeV,Γ(D01)=21.5 MeV, Γ(D′_1~±.)=232 MeV, Γ(D_1~±)=215 MeV, Γ(D′_(s1)~±)=0.0101 MeV, Γ(D~±s1)=0.950 MeV, Γ(B′_1~±)=263 MeV, Γ(B~±1) = 16.8 MeV, Γ(B′s1) = 0.01987 MeV and Γ(B_(s1)) = 0.412 MeV. It is found that the decay widths of D~±s1 and Bs1 are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.     

Hadronic coupling constants of the lowest hidden-charm pentaquark state,using QCD sum rules with rigorous quark-hadron duality

In this article,we illustrate how to calculate the hadronic coupling constants of the pentaquark states with QCD sum rules based on rigorous quark-hadron quality.We then study the hadronic coupling constants of the lowest diquark-diquark-antiquark type hidden-charm pentaquark state with spin-parity J~P=1/2~-in detail,and calculate the partial decay widths.The total width Г(P_c)=14.32±3.31 MeV is compatible with the experimental value T_(P_c(4312))=9.8±2.7_(-4.5)~(+3.7) MeV from the LHCb collaboration and favors assigning the P_c(4312) to be the [ud][uc]c pentaquark state with J~P=1/2~-.The hadronic coupling constants have the relation ■,and favor the hadronic dressing mechanism.The P_c(4312) may have a diquark-diquark-antiquark type pentaquark core with the typical size of the qqq-type baryon states.The strong couplings to the meson-baryon pairs DE_c lead to some pentaquark molecule components,and the P_c(4312) may spend a rather large time as the DE_c molecular state.     

Measuring D~0-~0mixing in D→f_0(980)K~* and more

We investigate the D0-0 mixing through the doubly Cabibbo suppressed (DCS) channel D0 →f0(980)K0 and its charge conjugate channel, in which the K0 meson is reconstructed in both K π- and KSπ0 final state. Although the decay D0 →f0(980)K* has a small branching ratio, the final state mesons are relatively easy to identify. The f0(980) meson can be replaced by the S-wave π π- state, or a longitudinally polarized vector meson ρ0. All mixing parameters, including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels. We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Study of radially excited D_s(2~1S_0) and D_s(3P )

The unobserved J~P= 0~-radial excitation D_s(2~1S_0) is anticipated to have mass 2650 Me V(denoted as D_s(2650)). Study of hadronic production is an important way to identify highly excited states. We study hadronic production of D_s(2650) from higher excited resonances in a3P0 model. Relevant hadronic partial decay widths are found to be very small, which implies it is difficult to observe D_s(2650) in hadronic decays of higher excited resonances. Hadronic decay widths of radially excited D_s(3P) have also been estimated. The total decay widths of four D_s(3P) are large, but the branching ratios in the D_s(2650)η channel are very small, which implies that it seems impossible to observe D_s(2650) in hadronic decays of D_s(3P). The dominant decay channels of the four D_s(3P) have been pointed out, and D_1(2420), D_1(2430), D*2(2460), D(2550), D(2600),(1~1D_2)D(2750) and D_3*(2760) are possible to observe in hadronic production from D_s(3P).     

Analysis of the coupling constants g_(a_0ηπ~0 )and g_(a_0η'π~0) with light-cone QCD sum rules

Abstract In this article, we take the point of view that the light scalar meson a_0(980) is a conventional qq state, and calculate the coupling constants g_(a_0ηπ~0) and g_(a_0η'π~0) with the light-cone QCD sum rules. The central value of the coupling constant g_(a_0ηπ~0) is consistent with that extracted from the radiative decay φ(1020) → a_0(980)γ→ηπ~oγ. The central value and lower bound of the decay width Γ_(α_0→ηπ~0) = 127_(-48)~(+84) MeV are compatible with the experimental data of the total decay width Γ_(α_0(980))= (50-100) MeV from the Particle Data Group with a very model dependent estimation (the decay width can be much larger), while the upper bound is too large. We give a possible explanation for the discrepancy between the theoretical calculation and experimental data.     

Radial excitation states of η and η′ in the chiral quark model

A chiral quark model is applied to calculate the spectra of pseudoscalar mesons η and η . By analyzing the obtained spectra, we find that the mesons η (2 1 S 0 ), η(4 1 S 0 ), η (3 1 S 0 ) and η (4 1 S 0 ) are the possible candidates of η(1760), X(1835), X(2120) and X(2370). The strong decay widths of these pseudoscalars to all the possible two-body decay channels are calculated within the framework of the 3 P 0 model. Although the total width of η (21S0 ) is compatible with the BES Collaboration’s experimental value for η(1760), the partial decay width to ωω is too small, which is not consistent with the BES result. If X(1835) is interpreted as η(4 1 S 0 ), the total decay width is compatible with the experimental data, and the main decay modes will be πa 0 (980) and πa 0 (1450), which needs to be checked experimentally. The assignment of X(2120) and X(2370) to η (31S0 ) and η (41S0 ) is disfavored in the present calculation because of the incompatibility of the decay widths.     

Light meson spectrum and their leptonic decay widths in the frame work of constituent quark models

The phenomenological non-relativistic quark model has been employed to obtain the ground state masses of light vector mesons and their radially excited states and their decay widths.The full hamiltonian used in the investigation has kinetic energy,the confinement potential and the one-gluon-exchange potential.A good agreement is obtained with the experimental masses and their leptonic decay widths.     

Decay rates of charmonia within a quark-antiquark confining potential

In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic Schro¨dinger equation by employing an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are employed to compute the spectroscopy of the excited S states and a few low-lying P and D waves. The resultant wave functions at zero interquark separation as well as some finite separations are employed to predict the di-gamma, di-leptonic and di-gluon decay rates of charmonia states using the conventional Van Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also computed by incorporating the relativistic corrections of order v4 within the NRQCD formalism.We have observed that the NRQCD predictions with their matrix elements computed at finite radial separation yield results which are found to be in better agreement with experimental values for both di-gamma and di-leptonic decays.The same scenario is seen in the case when di-gamma and di-leptonic decay widths are computed with the Van RoyenWeisskopf formula. It is also observed that the di-gluon decay width with the inclusion of binding energy effects are in better agreement with the experimental data available for 1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are also predicted. Thus, the present study of decay rates clearly indicates the importance of binding energy effects.     

Vector meson J/ψ, Ф electro-production in QCD

We study the vector meson electro-production off the proton in a QCD inspired model. A calculation of the differential cross section is performed for the J/ψ, Ф meson off the proton. The theoretical results are consistent with the experimental data, and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section. Since gluons interact among themselves via self-interaction, the gluons can form a glueball with quantum numbers I^G, J^PC = 0^＋, 2^＋＋ with a decay width Гt = 100 MeV and mass of mG = 2.23 GeV. The three gluons can form a three gluon color bound state with charge conjugation quantum number C = -1. This study is quite important to verify the validity of QCD and to search for new particles （tensor glueball and Odderon） as well as quest for new physics.     

Measuring DO-D-O mixing in D→Fo(980)K* and more

We investigate the DO-D-O mixing through the doubly Cabibbo suppressed (DCS) channel DO→fO(980)K*O and its charge conjugate channel,in which the K*O meson is reconstructed in both K+π- and KsπO final state.Although the decay DO→ fo(980)K* has a small branching ratio,the final state mesons are relatively easy to identify.The fo(980) meson can be replaced by the S-wave π+π- state,or a longitudinally polarized vector meson pO.All mixing parameters,including the mass difference and decay width difference,can be extracted by studying the time-dependent decay width of these channels.We show that the method is valid in all regions for mixing parameters and it does not depend on the strong phase difference.     

Vector meson J/ψ,φ electro-production in QCD

We study the vector meson electro-production off the proton in a QCD inspired model.A calculation of the differential cross section is performed for the J/ψ,φ meson off the proton.The theoretical results are consistent with the experimental data,and remind us to consider the contribution from the tensor glueball and Odderon to the differential cross section.Since gluons interact among themselves via self-interaction,the gluons can form a glueball with quantum numbers IG,JPC =0+,2++,with a decay width Γt =100 MeV and mass of mG = 2.23 GeV.The three gluons can form a three gluon color bound state with charge conjugation quantum number C =-1.This study is quite important to verify the validity of QCD and to search for new particles(tensor glueball and Odderon) as well as quest for new physics.     

Strong decays of the low-lying bottom strange baryons

In this work,the strong decay behaviors of the λ-mode low-lying Ξ_b and Ξ'_b baryons are investigated within the ~3 P_0 model.Our results suggest that all of the low-lying 3_F states Ξ_b(2 S),Ξ_b(1 P),and Ξ_b(1 D) have small decay widths of less than 20 MeV,and these states have good potentials to be observed in the Ξ'_bπ and Ξ'_b~*π invariant masses.Further,most of the 6_F multiplets are relatively narrow and may decay into the Ξ_bπ,Ξ'_bπ,Ξ'_b~*π,and Δ_bK final states.Considering the masses and strong decay behaviors,we can assign the newly observed Ξ_b(6100) resonance as the Ξ_b(1 P) state with J~P=3/2~-and interpret the Ξ_b(6227)structure as the J~P=3/2~-Ξ'_b(1 P) state with a proper mixing angle.We expect that our predictions for these excited bottom strange baryons will provide helpful information for future experimental research.     

Exotic vector charmonium and its leptonic decay width

We propose a novel type of interpolating field operator,which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonic degrees of freedom.A heavy vector charmonium-like state with a mass of 4.33(2) GeV is disentangled from the conventional charmonium states in the quenched approximation.This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator.We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of J/ψ,which corresponds to a leptonic decay width about dozens of eV.The connection of this state with X(4260) is also discussed.     

Dibaryon Mass and Width Calculation with Tensor Interaction

The effect of tensor interaction due to gluon and Goldstone boson exchange on the dibaryon mass and decay width has been studied in the framework of the quark delocalization and colour screening model. The effective S-D wave transition interactions induced by gluon and Goldstone boson exchanges decrease quickly with the increasing channel strangeness, and there is no six-quark state in the light flavour world, which can become a bound one by the help of these tensor interactions, except for the deuteron. The K and η meson exchange effect has been shown to be negligible after a short-range truncation in this model approach. The partial D-wave decay widths, from the NΩ state to the AΞ final states of spins 0 and 1, are 20.7 keV and 63.1 keV respectively. This is a very narrow dibaryon resonance, that might be detected in the relativistic heavy ion reaction by the existing RHIC detectors through the reconstruction of the AΞ vertex mass and by the future COMPAS detector at CERNand the FAIR project in Germany.     

Dynamics of strong and radiative decays of D_s-mesons in the hadrogenesis conjecture

The positive parity scalar D ＊ s0 （2317） and axial-vector D ＊ s1 （2460） charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D（D s ）-meson ground states.The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian.Chiral corrections to order Q 2 χ are calculated and found to be small.The D ＊ s0 （2317） and D ＊ s1 （2460） mesons decay either strongly into the isospin-violating π 0 D s and π 0 D ？ s channels or electromagnetically.We show that the π 0-η and （K^ 0 D ^＋-K^ ＋ D^ 0 ） mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the KD component of the states.The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q 2 χ .We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays.The radiative width are sensitive to both η D s and KD components,hence providing information complementary to the strong widths on the positive parity D s-meson structure.     

A family of double-beauty tetraquarks: Axial-vector state ■

The spectroscopic parameters and decay channels of the axial-vector tetraquark ■(in what follows,■ are explored using the quantum chromodynamics(QCD) sum rule method.The mass and coupling of this state are calculated using two-point sum rules by taking into account various vacuum condensates,up to 10 dimensions.Our prediction for the mass of this state m=(10215±250) MeV confirms that it is stable with respect to strong and electromagnetic decays and can dissociate to conventional mesons only via weak transformations.We investigate the dominant semileptonic ■ and nonleptonic ■ decays of ■.In these processes,■ is a scalar tetraquark ■ built of a color-triplet diquark and an antidiquark,whereas M is one of the vector mesons ρ~-,K~*(892),D~*(2010)~-,and D_s~(*-).To calculate the partial widths of these decays,we use the QCD three-point sum rule approach and evaluate the weak transition form factors G_i(i=0,1,2,3),which govern these processes.The full width Γ_(full)=(12.9±2.1) × 10~(-8) MeV and the mean lifetime τ=5.1+_(-0.71) ~(+0.99) fs of the tetraquark ■ are computed using the aforementioned weak decays.The obtained information about the parameters of ■ and ■ is useful for experimental investigations of these double-heavy exotic mesons.     

Prediction of possible exotic states in the η■K~* system

We investigate the ηKK~*three-body system in order to look for possible IG(J~(PC))=0~+(1~(-+)) exotic states in the framework of the fixed-center approximation of the Faddeev equation.We assume the scattering of η on a clusterized system KK~*,which is known to generate f_1(1285),or a K in a clusterized system ηK~*,which is shown to generate K_1(1270).In the case of η-(KK~*)f_1(1285) scattering,we find evidence of a bound state IG(J~(PC))=0~+(1~(-+)) below theηf_1(1285) threshold with a mass of around 1700 MeV and a width of about 180 MeV.Considering K-(η/K~*)K_1(1270)scattering,we obtain a bound state I(J~P)=0(1~-) just below the KK_1(1270) threshold with a mass of around 1680 MeV and a width of about 160 MeV.